- You need to know where mail actually lands. Unspam delivers to real seed inboxes at Gmail, Outlook, Yahoo, Zoho, ProtonMail, AOL and GMX and reports inbox vs spam per provider. Email on Acid's spam test returns a pass/fail score against 23 filters and a blocklist check, not a per-provider placement report.
- You want an AI eye-tracking heatmap and an AI assistant. Email on Acid has neither: it checks rendering and accessibility, not where attention goes or what to fix.
- You want client previews on a plan that stays free. Unspam renders across 50+ real clients and devices, each in light and dark mode, and its free plan includes 3 device previews every month (10 on Basic).
- You'd rather pay $0.20 a screenshot from a $5 monthly minimum than $99/mo for Email on Acid's entry plan, or use a free tier with no card.
- You want results in about 30 seconds and a 14-day no-questions-asked refund on every paid plan.
An Email on Acid alternative that adds real-seed inbox placement and AI heatmaps
Email on Acid is a QA and rendering-preview platform, now sold as Mailgun Inspect: it shows how an email looks across 100+ clients and runs pre-send checks for accessibility, links, images and spam content, with plans listed from $99/mo. Unspam tests where the email lands, not just how it renders: real-seed inbox placement, spam scoring, client previews and AI eye-tracking heatmaps in one plan, free to start and paid from $5/mo.
Compared from public pricing and product pages, September 2026.
Which one fits you?
- You need the broadest rendering coverage. Email on Acid previews 100+ clients and devices, including dark mode, which is deeper than Unspam's preview set.
- You want a guided pre-send QA checklist. Campaign Precheck walks a team through preheader, accessibility, link and image validation and spell check in one workflow. Unspam has no equivalent checklist automation.
- You need dedicated accessibility (ADA) checks and a self-serve preview API. Email on Acid has both; Unspam has no accessibility checker and its API is on the Custom plan only.
Why teams move from Email on Acid to Unspam.
Placement data, not just rendering
Email on Acid shows how an email renders across 100+ clients and runs a pass/fail spam test against 23 filters with a blocklist check, but it does not report where mail lands per provider. Unspam delivers test emails to real seed inboxes at Gmail, Outlook, Yahoo, Zoho, ProtonMail, AOL and GMX and shows inbox vs spam for each, alongside the spam score.
Heatmaps and an AI assistant in the same plan
Email on Acid has no attention heatmap and no AI fix assistant: its strengths are previews, accessibility and the pre-send checklist. Unspam adds an AI eye-tracking heatmap and an AI assistant that explains what to fix on every plan, including the free one, with results in about 30 seconds.
Lower entry price and a real free tier
Email on Acid starts at $99/mo with a free trial but no permanent free plan, and now sells its plans as Mailgun Inspect (also from $99/mo). Unspam's paid pricing starts at $5/mo with a 14-day no-questions-asked refund, and the free plan renews monthly with no card, including 3 client previews a month across 50+ real clients in light and dark mode.
Unspam vs Email on Acid, feature by feature.
Based on public product pages and documentation. Spotted something outdated? Tell us in the chat and we'll fix it.
Feature
Unspam
Email on Acid
Free plan or trial
Free plan, no card
Free trial only, no free plan
First paid plan
$5/mo minimum, usage-priced
$99/mo
Spam score testing
Yes
Yespass/fail against 23 filters, blocklist check in Campaign Precheck
Inbox placement tests
Yes
Partialspam/filter test, not per-provider placement report
Client previews & screenshots
Yes50+ clients, light & dark
Yes90+ to 100+ clients and devices
AI attention heatmap
Yes
No
Blacklist monitoring
Partialon-demand checker
Partialdomain/IP blocklist check per test
SPF / DKIM / DMARC checks
Yes
PartialSPF/DKIM/DMARC flagged within spam test
AI fix recommendations
Yes
No
Scheduled automatic tests
Yesplacement + spam score
No
Scheduled spam score tests
Yesdaily, weekly, or monthly
NoCampaign Precheck runs before a send, not on a schedule
Sender accounts
YesUnlimited
No
API access
YesCustom plan
Yes
MCP server
YesCustom plan
No
Email verification
Yes
No
Automated inbox warmup
No
No
DMARC report monitoring
YesCustom plan, first domain free
No
Deliverability consulting
Yesseparate service
No
Compared from public pricing and product pages, September 2026.
What each one costs.
Email on Acid is owned by Sinch and its plans are now sold as Mailgun Inspect: Basic $99/mo and Premium $199/mo, both with unlimited users and a monthly preview cap (1,000 and 2,000) rather than unlimited previews, plus a custom Contract tier. Extra previews are $0.15 each, and one preview means one client or device screenshot. The vendor's pricing page offers a currency selector for USD, EUR and GBP and no annual discount. A free trial is available; there is no permanent free plan. Existing subscribers began transitioning to Mailgun Inspect starting June 2026.
- Free $0
5 spam tests, 3 inbox placements, 3 device previews, 5 screenshots, 5 heatmaps per month. AI assistant included.
- Custom $5/mo
Pay per test: spam tests $0.18, inbox placements $0.50, device previews $0.75, screenshots $0.20, heatmaps $0.30. Volume discounts to 30%, 15% off annual, $5 monthly minimum. API, MCP and three years of history included. DMARC monitoring is $6 per domain per month, first domain free.
- Basic $99/mo
unlimited users, 1,000 previews/mo across 100+ clients and devices, API access
Sold as Mailgun Inspect; $0.15 per extra preview.
- Premium $199/mo
unlimited users, 2,000 previews/mo across 100+ clients and devices, API access, accessibility tests, HTML code analysis, link and image validation, spam content checks
Sold as Mailgun Inspect; $0.15 per extra preview.
- Contract Custom pricing (contact us)
unlimited users, custom previews allotment across 100+ clients and devices, API access, accessibility tests, HTML code analysis, link and image validation, spam content checks, phone and chat support
Every Email on Acid plan and price in full
Compared from public pricing and product pages, September 2026. Email on Acid is a trademark of its respective owner. Unspam is not affiliated with or endorsed by Email on Acid.
Unspam vs Email on Acid, answered.
Is Unspam a full replacement for Email on Acid?
Partly. For spam scoring and inbox placement, Unspam goes further: it delivers to real seed inboxes at 7 providers and reports inbox vs spam, and adds an AI heatmap and AI assistant. But Email on Acid is stronger at rendering breadth (100+ clients), its guided pre-send QA checklist and dedicated accessibility (ADA) checks, which Unspam does not offer. Neither tool does inbox warmup, and ongoing DMARC report monitoring is Unspam only, on the Custom plan.
How does the pricing compare?
Email on Acid is now sold as Mailgun Inspect from $99/mo (Basic, 1,000 previews), with Premium at $199/mo (2,000 previews) and a custom Contract tier, and a free trial but no free plan. Unspam charges per test instead, from a $5 monthly minimum: $0.20 a screenshot, $0.18 a spam test, with a 14-day refund and 15% off annual billing. See pricing. Vendor scope has moved fast in this category, from Litmus retiring its entry tiers to this migration, so check which vendors changed scope in the last two years before you trust an older review.
What is the biggest functional difference?
Email on Acid tests how an email looks and whether it passes a pre-send checklist; Unspam tests where it goes. Unspam runs real-seed inbox placement across Gmail, Outlook, Yahoo, Zoho, ProtonMail, AOL and GMX, plus spam scoring, client previews across 50+ real clients in light and dark mode, and an AI heatmap. Email on Acid's spam test is a pass/fail filter and blocklist check, not a per-provider placement report.
Do the free tiers compare?
Email on Acid offers a free trial but no permanent free plan. Unspam's free plan renews every month with 5 spam tests, 3 inbox placements, 3 device previews, 5 screenshots and 5 heatmaps, with the AI assistant included and no credit card required.